Legal Definitions - lay opinion testimony

Lay opinion testimony refers to a statement made in court by an ordinary witness (someone who is not an expert) that expresses an opinion or inference, rather than a direct factual observation. For this type of testimony to be admissible, the opinion must be rationally based on the witness's own perceptions, and it must be helpful in clearly understanding the witness's testimony or in determining a fact in issue. Unlike expert testimony, which relies on specialized knowledge, lay opinion testimony is based on observations that an average person could make and interpret.

• Example 1: Describing a Person's Emotional State

  During a trial concerning an altercation, a witness testifies, "After the argument, the defendant looked absolutely furious; his face was red, and his fists were clenched."

  This illustrates lay opinion testimony because the witness is not a psychologist or an expert in human emotions. However, their opinion that the defendant "looked absolutely furious" is rationally based on their direct observation of the defendant's physical appearance and demeanor (red face, clenched fists). This opinion helps the court understand the defendant's state of mind immediately following the argument.

• Example 2: Estimating the Speed of a Vehicle

  In a traffic accident case, a bystander who witnessed the collision states, "The blue car was traveling at a tremendous speed, easily over 70 miles per hour, just before it hit the intersection."

  Here, the witness is not a traffic engineer or equipped with a radar gun. Their opinion about the car's "tremendous speed" and estimation of "over 70 miles per hour" is a lay opinion. It is based on their common experience and perception of moving vehicles, and it helps the court understand the circumstances leading to the accident.

• Example 3: Identifying a Voice from Familiarity

  In a criminal case involving an anonymous phone call, a police officer testifies, "I've known the suspect for over ten years and have spoken to him hundreds of times. That's definitely his voice on the recording."

  This is lay opinion testimony because the officer is not a forensic voice analyst. However, their opinion identifying the voice is rationally based on their extensive personal familiarity with the suspect's voice over many years. This opinion is helpful in establishing the identity of the person making the phone call.